/Engine/Plugins/Runtime/AudioWidgets/Source/AudioWidgets/Public/AudioRadialSlider.h
Sets the start and end of the hand as a ratio to the slider radius (so 0.0 to 1.0 is from the slider center to the handle).
[UFUNCTION](Programming/UnrealArchitecture/Reference/Functions)(BlueprintCallable, Category="Appearance") void SetHandStartEndRatio ( const FVector2D InHandStartEndRatio )